Patent GB-222505-A (GB)
Title: Improved ciphering apparatus
IPC: G09C1/04
Filed: 1924-09-27
Abstract: 222,505. Aktiebolaget Cryptograph. Sept. 28, 1923, [Convention date]. Ciphers. - In ciphering-apparatus involving similar manipulations for each ciphering or deciphering operation, the sign substitutes in successive operations are determined by the cooperation of four members; the first member carries a set of signs and can take up two different positions relatively to a reading aperture and to the second member, which is rotated a certain angle at' each operation and carries a series of sets of signs, and the third member represents an arbitrary series of figures and is rotatable to operate the fourth member and move it a predetermined, distance, the fourth member representing another arbitrary series of figures and determining by its position the position of the first member. The second member may comprise discs 3 joined by rods and removably mounted on a rotatable, shaft 2 in a casing 1, a series of alphabet bars 5 being detachably mounted in variable order around the discs 3. The shaft 2 may be rotated by a knob 33, but is rotated at each ciphering operation by a handle 9 which carries a pawl 8 engaging a ratchetwheel 6 on the shaft 2, and which is normally raised by a spring 10. Each depression of the handle 9 rotates the wheel 6 two teeth and a second ratchet-wheel 11 one tooth, the number of teeth in the wheel 6 being greater than the number in the wheel 11 and equal to the number of bars 5. The wheel 11 carries a flange 16 with signs visible through an aperture to enable its position to be observed, and a wheel 12 with radial holes equal in number to the number of teeth in the wheel 11. The holes receive pins 15 arbitrarily arranged and the wheel 12 is removably held in position by a nut 13 and locknut 14 to allow rearrangement of the pins. The pins 15 operate a wheel 20 with eight teeth, the wheel 20 carrying an octagonal prism 23 around which passes a chain 24 with thin and thick links arbitrarily arranged. A roller 26 rests on the links and controls according to whether a thin or thick link is beneath it, and through arms 27, 29 and a link 30, the position of a spring-urged U-shaped part 31. The part 31 constitutes the first of the ciphering members and carries an alphabet above the bars 5 and beneath an aperture 34 in the casing of width equal to that of two bars 5. Substitutions are determined by corresponding signs visible at the aperture 34, one: on the part 31 and one on a bar 5. The sets of signs on the part 31 and the bars 5 may be in reversed order or arbitrarily reciprocal, deciphering then being identical with ciphering, or may be relatively irregular, corresponding ciphering and deciphering substitutions then being determined between the part 31 and the bars 5 in reverse order. An odd number of bars 5 is preferably used, and arbitrarily chosen bars may be omitted or may bear no alphabet, the depression of the handle 9 being repeated when one of these appears at the aperture 34. The alphabets on the bars 5 may be relatively displaced around the discs 3 in opposite direction to that of the rotation of the discs. To facilitate rearrangement or exchange of the members influencing the cipher, the end walls 35. 36 of the casing 1 are removable and the wall adjacent to the chain 24 is hinged at 37.